Selective completion using triple wrap screen

ABSTRACT

This invention relates to a completion system for a well drilled in the earth and especially for a well drilled to an oil and gas producing formation. It relates to a system for selectively producing fluid from either an upper or lower zone and for providing sand control facilities for each zone. A tubing string is suspended in a well bore and has an upper sand screen and a lower sand screen which are adjacent the upper and lower producing zones respectively. A packer is set in the annulus about the tubing between the two sand screens. An upper sleeve valve is mounted in the tubing string and is surrounded by the upper sand screen. Plug valve means are provided in the tubing string between the two sand screens. By selectively opening or closing the sleeve valve and the plug valve, production can be selectively opened from either the top or lower zones or both.

United States Patent [191 Wolff et al.

[ 1June 26, 1973 SELECTIVE COMPLETION USING TRIPLE WRAP SCREENInventors: Charles S. Wolff; Michael J.

Jeansonne, Lake Charles, La.

Assignee: Amoco Production Company, Tulsa,

Okla.

Filed: Nov. 10, 1971 Appl. No.: 197,241

US. Cl. 166/184, 166/234 Int. Cl E2lb 33/124 Field of Search 166/184,313, 224,

v References Cited Y UNITED STATES PATENTS 6/1954 Tapprneyer 166/3135/1966 Donaldson et a1 166/228 2/1957 Maly et al 166/313 9/1960 Garrett166/313 2/196l Daffin et al 166/224 Primary Etrqgni rtgr- James A.Leppink A ttorney- Paul F. Hawley and John D. Gassett [57] ABSTRACT Thisinvention relates to a completion system for a well drilled in the earthand especially for a well drilled to an oil and gas producing formation.It relates to a system for selectively producing fluid from either anupper or lower zone and for providing sand control facilities for eachzone. A tubing string is suspended in a well bore and has an upper sandscreen and a lower sand screen which are adjacent the upper and lowerproducing zones respectively. A packer is set in the annulus about thetubing between the two sand screens. An upper sleeve valve is mounted inthe tubing string and is surrounded by the upper sand screen. Plug valvemeans are provided in the tubing string between the two sand screens. Byselectively opening or closing the sleeve valve and the plug valve,production can be selectively opened from either the top or lower zonesor both.

3 Claims, 2 Drawing Figures SELECTIVE COMPLETION USING TRIPLE WRAPSCREEN RELATED PATENT APPLICATIONS This application is related toco-pending patent application Ser. No. 77,492 filed Oct. 2, 1970,entitled Multilayer Well Screen for William G. Bearden and George C.Howard.

BACKGROUND OF THE INVENTION This invention relates to a well completionsystem for selectively producing fluids from either an upper or lowerzone and in which these zones produce fluids containing sand. It relatesespecially to a system for producing fluid selectively from either zonethrough special sand filters.

SETTING OF THE INVENTION Oil and gas are produced from undergroundformations through well bores drilled from the surface to the formation.Sometimes oil and gas are found in the pores of consolidated rocks orsand. When this oil is produced through the well bore, it is relativelyfree of any particles or sand. However, many oil and gas wells producefluid from underground formations which are not consolidated; that is,the various sand particleswhich make up the rock are not stronglyattached to each other. In such formations when the fluid is produced,it carries entrained sand with it. This sand causes serious damage towell equipment and greatly restricts production of such fluids. Inproducing oil and gas from such underground formations, some method mustbe provided to restrain the sand inflow into the well. Perhaps the mostwidely used method of preventing the inflow of sand is the use of agravel pack placed in the annular space in the well bore between aslotted liner and the formation. The voids between the gravel grains issmall enough to prevent inflow of sand particles but still permits flowof fluid.

In conventional gravel packing technique, a perforated liner isconnected to the lower end of a string of tubing which is suspended inthe well bore. Gravel is circulated (or carried) into the annular spaceabout the liner with the aid of a circulating fluid. This is usually atime consuming and very expensive operation. After the liner is placedin the well, washed and closely sized gravel is circulated into the wellat the surface a little at a time, to a stream of circulating fluidforced down the well under pump pressure. Normally the fluid andentrained gravel are forced downwardly through the string of tubing. Thegravel is discharged into the well cavity around the liner and thecirculating fluid returns to the surface through the annular space.Reverse circulation can be used in which the descending stream of fluidand entrained gravel passes down through the annular space between thetubing string and the casing, the gravel being deposited in the wellcavity and the fluid being returned to the surface through the string oftubing.

Frequently two vertically separated zones containing oil and gas are notpermitted by government regulations to be produced simultaneously wherethe fluid can co-mingle in the wellbore. Occasionally it is desired tocomplete a well selectively such that when the lower producing zone hasbeen depleted, the upper (selective) zone can be recompleted to withouta rig workover. This means that upon original conventional gravelpacking completion, the wellbore must be set up such that two intervalsare perforated (one set. of perforations at each productive zone) with agravel pack and SxL (sand control means) opposite each set ofperforations. This will ordinarily require about four round trips to setup the completion in the above manner. A round trip is the running(lowering) and pulling of an entire assembly (such as a string oftubing) with a rig on location. Rig time can cost $50 to $60 per hourfor wells located on land. Furthermore, special and costly equipment inthe form of packers and wash pipes are necessary in the conventionalgravel packing method. This gravel packing procedure is successful inmost cases but is time consuming and expensive. The present inventiondiscloses a system for selectively producing from either an upper orlower zone whereby all the equipment necessary for controlling sandproduction and for switching from one zone to the other is set when thestring of tubing is first run in the well bore. All that is requiredthereafter is wireline work in which the selective sleeves are changedin position in order to allow switching from one zone to another. Thisis accomplished without a rig and is therefore relatively inexpensive.

BRIEF DESCRIPTION OF THE INVENTION This invention concerns a wellcompletion system in which a casing is set through an upperunconsolidated formation and a lower unconsolidated formation. Thecasing has upper perforations and lower perforations at the elevation ofthe two zones. A string of tubing is suspended in the well bore. Thetubing string contains a sleeve valve which is set adjacent the upperperforations of the casing. A first sand screen surrounds this sleevevalve. The lower end of the tubing string is connected to a second orlower sand screen. A plug valve is set in the tubing string between thetwo sand screens. The sleeve valve and this plug valve means areoperable from the surface. A packer is set about the tubing between thetwo sand screens. Thus, by selectively opening or closing the sleevevalve and the plug valve, production can be had from either the upper orlower zone.

BRIEF DESCRIPTION OF THE DRAWINGS Various objectives and a betterunderstanding can be had of the invention by the following description,taken in conjunction with the drawings in which:

FIG. 1 is a schematic drawing of a well completion according to thisinvention.

FIG. 2 illustrates in greater detail the upper sand screen andassociated sleeve valves.

BETAILED DESCRIPTION OF THE INVENTION Attention is first directed toFIG. 1 which shows a well bore 10 having casing 12 which is set throughan upper petroleum productive zone 14 and a lower producing zone 16separated by a non-productive layer 15 such as shale. Zones l4 and 16are each unconsolidated zones, i.e. In the absence of preventativeaction, entrained sand is produced with the produced fluid. Casing 12has upper perforations 18 and lower perforations 20 which are at theelevation of zones 14 and 16 respectively.

A tubing string 22, through which the fluid is to be produced, issuspended in the well bore. The tubing string, sometimes called a"completion string", is provided with an upper sand screen 24 and alower sand screen 26 which are placed at about the levels ofperforations I8 and perforations 20 respectively. These sand screens area special type sand screen which is described in co-pending applicationSer. No. 77,492 supra. These are special type multi-layer filters whichhave been found in many cases to be more efficient and longer lastingthan gravel pack. In most cases no gravel packing is needed with thesemulti-layer sand screens. Typically these screens comprise a filter of aplurality of concentric screens spaced radially from one another, theopening in any one screen being no larger than the openings in anyscreen of larger diameter and no smaller than the openings in any screenof smallerdiameter. An upper packer 28 is provided in the annulus abouttubing string 22 at a point slightly above upper screen 24. A lowerpacker 30 is placed about tubing 22 between screens 24 and 26. Variouspackers are suitable for this operation. For example, the packerdesignated Husky M-l manufactured by Brown Oil Tool of 7400 E. SlausonAvenueLos Angeles, Calif. is quite suitable for packer 28 and a BrownOil Tool packer model DBL is quite suitable for packer 30.

Tubing 22 is provided with two valves which permits the upper part ofthe tubing string to be in fluid communication with either the interiorof the upper or lower sand screens. As shown in FIG. 2 this includes asleeve valve or valves 32 which is inserted in the tubing stringinterior of upper screen 24 and a valve means or plug means 34 in thetubing string between the two sand screens. A suitable valve 32 is amodel L sliding sleeve valve commercially available from Baker OilTools, Inc. A suitable plug means 34 is designated a Model F non portedseating nipple, also available from Baker.

Attention is directed to FIG. 2 for a more detailed illustration for anupper sand screen 24. As can be seen, this sand screen is placed about aslotted liner and has an inner layer 42, an intermediate layer and anouter layer 46. Each of these layers are formed preferably by wire woundin a spiral with selected spacing between the adjacent turns all asdescribed in said application Ser. No. 77,492. The upper end and thelower end of the annulus between tubing 22 and the filter are closed byany means such as bushings with o-rings or packing 23 and 25.

Referring back to FIG. 1, a pump 48 or any other type artificial lift,if needed, can be provided above packer 28. The equipment shown in FIG.1 permits sand free fluid to be produced selectively from either theupper or lower zones. The sleeve valve 32 and the plug valve 34 can beopened or closed from the surface using simple wireline equipment.

The equipment shown in FIG. 1 can all be set on one trip after the lowerpacker has been set by wireline. [If desired, both packers and thecompletion string can be run on the same trip. All that is necessary inthis case is to use compatible packers, i.e. a mechanical packer (suchas Brown Oil Tool Husky) as the lower packer and a hydrostatic (such asBaker Oil Tools, Inc. Model FH) packer as the upper packer. In thismethod wireline work is eliminated.) Lower sand screen 26 is supportedat this stage from packer 30 by tailpipe 27. All that is then necessaryis running the completion string (tubing 22, screen 24, plug 34, packer28 etc.) in sequence as is shown on FIG. 1. (All components screw intoeach other.) When the completion string is in the hole, a seal assemblyin the tubing string below plug 34 and not specifically shown, is stunginto the lower packer 30. The upper packer is then set by weight and-/or rotation. The tubing is then hung off in the tree and the wellplaced on production. Specific details of each step of this runningoperation are not given as they are known to those skilled in the art.

While the above description has been made in detail, variousmodifications can be made thereto without departing from the spirit orscope of the invention.

We claim:

1. A system for completing a well having an upper unconsolidatedproducing formation and a lower unconsolidated producing formation whichcomprises:

' a casing having upper perforations and lower perforations at theelevations of said upper and lower formation respectively;

a string of tubing in said casing, said string having no other stringwithin its interior;

a sleeve valve in said string of tubing at theelevation of said upperzone,

an upper sand screen surrounding said sleeve valve;

a lower sand screen connected to the lower end of said string of tubing;

a packer placed about said string of tubing between said upper and saidlower sand screen filters;

a tubing valve means at a selected location in said string of tubingbetween said sleeve valve and said lower sand screen operable from thesurface to open or close said string of tubing at said selectedlocation.

2. A system as defined in claim 1 including a packer about said tubingstring above said upper sand screen.

3. A system as defined in claim 1 in which said upper and lower sandscreens each comprise a filter of a plurality of concentric screensspaced radially from one another, the opening in any one screen being nolarger than the openings in any screen of larger diameter and no smallerthan the openings in any screen of smaller diameter.

t ti 4! t t

1. A system for completing a well having an upper unconsolidatedproducing formation and a lower unconsolidated producing formation whichcomprises: a casing having upper perforations and lower perforations atthe elevations of said upper and lower formation respectively; a stringof tubing in said casing, said string having no other string within itsinterior; a sleeve valve in said string of tubing at the elevation ofsaid upper zone; an upper sand screen surrounding said sleeve valve; alower sand screen connected to the lower end of said string of tubing; apacker placed about said string of tubing between said upper and saidlower sand screen filters; a tubing valve means at a selected locationin said string of tubing between said sleeve valve and said lower sandscreen operable from the surface to open or close said string of tubingat said selected location.
 2. A system as defined in claim 1 including apacker about said tubing string above said upper sand screen.
 3. Asystem as defined in claim 1 in which said upper and lower sand screenseach comprise a filter of a plurality of concentric screens spacedradially from one another, the opening in any one screen being no largerthan the openings in any screen of larger diameter and no smaller thanthe openings in any screen of smaller diameter.